JPS61250969A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To improve electrolyte absorbing ability of a separator and increase battery performance by using thermoplastic resin fiber to which a plasma irradiation treatment is applied in a separator. CONSTITUTION:Thermoplastic resin fibers to which a plasma irradiation treatment is applied is used in a part or whole of a separator in which electrolyte is held. Oxygen, nitrogen, argon, or air can be used as atmosphere gas for the plasma irradiation treatment. The plasma irradiation is performed by operating a microwave generator having an output of 0.1-5.0kW under a degree of vacuum of 0.01-10torr of one of these gasses for 10sec-10min. By this treatment, since affinity and absorbing ability of the fiber to dilute sulfuric acid electrolyte are increased, electrolyte absorbing ability of the separator is improved and battery performance is increased.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention provides a positive electrode and a negative electrode using lead oxide as an active material.
This invention relates to a sealed lead-acid battery consisting of a separator that isolates these two electrodes, and a dilute sulfuric acid electrolyte held therein.

BACKGROUND OF THE INVENTION Conventionally, glass mats have been mainly used as separators for lead-acid batteries that use dilute sulfuric acid electrolytes.

However, in order to prevent short circuits due to falling of the positive electrode active material, it is necessary to make the separator bag-shaped, and for this purpose separators made of polyolefin or polyolefin and glass mat are also used.

In a sealed lead-acid battery, the electrode plates and separator are impregnated with electrolyte, and there is no free electrolyte, but in terms of battery performance, it is better to have a large amount of electrolyte, and from this point of view, separator materials with excellent liquid absorption properties are used. must be used. Although glass mats have good acid resistance and electrolyte retention ability, they cannot be made into a bag shape because they are weak against bending, and they are also expensive. Therefore, some or all of the glass fibers are replaced with thermoplastic resin fibers, such as polyethylene terephthalate.
A separator using resin fiber as a substitute was proposed.

Problems to be Solved by the Invention However, in order to improve the reliability of lead-acid batteries and reduce costs, it is sufficient to increase the blending ratio of resin fibers.
In that case, the resin fiber's affinity for the electrolyte deteriorates, and the separator's ability to absorb the electrolyte deteriorates, resulting in an increase in battery internal resistance, which adversely affects large current discharge characteristics and low-temperature characteristics. give. Therefore, when resin fibers are mixed with glass fibers, a liquid absorbing agent such as silica powder is added. However, in this case, powder is scattered during the process, which is not good for the working environment, and the material becomes non-uniform, which causes variations in performance as a separator.

The present invention solves these problems by improving the resin fibers constituting the separator, and aims to improve battery performance by improving the liquid absorption of the separator.

Means for Solving the Problems The present invention uses thermoplastic resin fibers that have been subjected to plasma irradiation treatment for part or all of the separator that holds the electrolyte.

The atmospheric gas during the plasma irradiation treatment of the resin fibers may be any of oxygen, nitrogen, argon, and air, and these may be used alone or in combination. These gases are kept under a vacuum of 0.01 to 10 torr, preferably 0.1 to 5 torr. □ Maintain torx, output 0.1~
5. OKW, preferably 0.5 to 2, OKW microwave generator for 10 seconds to 30 minutes, preferably 2 minutes to 1
Plasma irradiation can be performed by operating for 0 minutes. The frequency of the microwave generator here is 13.56 MHz,
2450MH2 may be used, and the resin fibers are subjected to plasma irradiation treatment under any conditions.

Resin fibers that have been treated with action plasma irradiation have a high affinity and absorbency for dilute sulfuric acid electrolyte, and lead-acid batteries using this as a separator have good compatibility with electrolyte and retain electrolyte well. Since it is not easily released, the hermeticity of lead-acid batteries can be improved.

Example The details of this invention will be explained below using one example.

The figure shows the liquid absorption properties of the separator. The separator is made of 70% polyethylene terephthalate resin fiber by weight.
The non-woven fabric was made of 20% glass fiber and 10% binder, and its thickness was 1 mm. This separator is cut into strips having a width of 3-1 and a length of 16, and the relationship between the elapsed time when the lower end of the separator is immersed in water and the liquid level height at that time is shown. Figure B uses the separator having the above-mentioned structure, and B uses the same amount of polyethylene terephthalate resin fibers that have been treated with microwave plasma irradiation.

In the plasma irradiation treatment using microwaves, the degree of vacuum was maintained at 1.0 Torr in an argon atmosphere, and microwaves with a frequency of 13.56 KH1 were applied for 3 minutes. Figure: Plasma irradiation by microwave 3°5txm
It can be seen that the liquid was absorbed only up to the height of , indicating that plasma irradiation treatment using microwaves is effective in increasing the liquid absorption.

Effects of the Invention As described above, if a separator containing resin fibers subjected to plasma irradiation treatment is used, it has excellent liquid absorption properties and can hold a large amount of electrolyte without being liberated. In addition, it can be easily made into a bag shape by thermally welding the three sides, which prevents short circuits due to the active material falling off.
Cost reduction is possible compared to glass fiber separators.

[Brief explanation of the drawing]

The figure is a diagram showing the liquid absorption performance of a separator of a sealed lead-acid battery according to an embodiment of the present invention. M: Untreated separator, B: Separator treated with plasma irradiation.

Claims (3)

[Claims] (1) A closed type device comprising a positive electrode, a negative electrode, a separator separating these two electrodes, and a dilute sulfuric acid electrolyte held therein, the separator containing thermoplastic resin fibers treated with plasma irradiation. Lead acid battery. (2) The sealed lead-acid battery according to claim 1, wherein the separator is made of polyethylene terephthalate resin fibers treated with plasma irradiation. (3) The sealed lead-acid battery according to claim 1, wherein the separator is mainly made of polyethylene terephthalate resin fibers treated with plasma irradiation, and is made of a nonwoven fabric of glass fibers and a binder.